The present invention concerns a containment, such as a glovebox, as used in the nuclear industry, in which the atmosphere in the containment must be kept isolated from the outside environment and in particular an extract system for use in connection with such a containment. Such extract systems enable the wastes and contaminants produced by operations in the containment to be extracted and filtered by suction from the containment. The pressure inside the containment is below atmospheric and this condition is known in the art as a "depression".